What contributes most to a change in how an amplifier sounds?

Reminds me a bit of the old story where organs of the body are having a fight over who was most important.  Can’t remember what the plot twist was — something like the little toe saving the day.

But the moral was the organs make up a team, all of which is “most important” depending on what is going on.

Don’t forget how you isolate them from resonance and vibrations. 

All of it contributes.  The weight of an amp is its most important spec.

About twenty years ago I bought a pair of old, used Altec-Lansing 1568A mono amplifiers in nice shape, they had spenent their lives in a rack.

Those 1568A’s are simple, lightly stressed designs, made to run 24 hours a day, using two EL34 tubes in a push-pull configuration to deliver a clean 40 watts.
They also have some of the finest transformers ever put in an amplifier, second only to the legendary output trannys found in the Harman-Kardon Citation II.
Any tube amplifier made today, regardless of price, except for some insanely expensive Ongakus, has transformers that cannot hold a candle to those on those Altecs and the H-K Citation.

But the Altecs also had anemic and primitive power supplies. Too simple.

Upgrading a tube amplifier power supply is really not too difficult, and these had plenty of room to work in.
So I went to town on these, replacing the PS caps with new oversize electrolytics with poyptopylene bypass caps.
I also also added a filter choke. A slight hum disappeared completely, All the signal caps were updated with Polypropes. All the resistors were replaced with new carbon films
Finally two NOS sets of Philips EL-34’s finished the job.

Those old Altecs put my McIntosh MC-60’s to shame. Greater slam in the bass, smoother mids, and the highs were just plan gorgeous, silky and detaled, into my JBL C50/S7 speakers.
I soon sold the Macs for $2000, and the total cost of those Altecs including the mods was about $700.00.

Downside: These Altec 1568A amplifiers are just plain ugly to look at.
Just put them somewhere you don’t have to see them.

Stock

Modded

Marc Stager
https://silversolids.com/